Occupants of a building, such as those of an office room, sometimes experience uncomfortable glare because natural outdoor light (sunlight) enters inside (the interior of the room) through, for example, a window pane (window glass). A window shade (window blind), a curtain, or the like may therefore be used over the window pane to prevent the occupants from experiencing glare during work and also out of privacy and security concerns. The use of these window coverings restricts light coming through the window pane and prevents people from peeping inside through the window pane.
Some window shades (for example, those described in Patent Literature 1) include slats each of which is composed of a first flat plate section and a second flat plate section at a predetermined angle and hence has an inverted V-shaped cross-section, in order to enhance the light-blocking function of the window shades. In this structure, the first flat plate section of each slat overlaps the first flat plate section of the slat that is immediately below that slat. The first fiat plate sections can therefore cover the whole window, which enhances the light-blocking function thereof.
Efforts have also been made to impart various functions other than the light-blocking function to the window shade. For example, tiny structures are formed on the slats (daylighting members) of a window shade to efficiently admit outdoor light during the daytime for projection of light in the direction of, for example, an indoor ceiling (see, for example, Patent Literature 2).
Patent Literature 2 discloses an assembly, attached to a slat via a support mount, that includes a light-guiding film sandwiched between a planar color-changing element and a planar shading element. In this structure, the support mount holding the planar assembly pivots to control its light-blocking and light-transmitting functions.